In preparing a string of tubing as it is lowered into a well bore, it is essential to conduct pressure tests of the tubing, including the pipe walls and all connection joints, to determine whether any leaks exist. It is well known to pressure test the connected string of tube sections, and the intermediate joints connecting those sections together by isolating a portion of the tubing through use of a tool inserted into the tubing, by expanding spaced-apart packers and then subjecting the isolated portion between the packers and the tool's exterior to high pressure. Leaks will then be detectable by conventional monitoring equipment used with such testing tools.
The testing tool itself is normally either supported from a cable and inserted into and removed from the tubing between each test, or is allowed to ride within the tubing sections being formed and is pulled upwardly from a lower section that has been tested into a new section mounted on the previous section in order to check the new upper section.
The following U.S. patents illustrate exemplary developments in the art of pressure testing tools:
G. L. Loomis, U.S. Pat. No. 3,154,940 PA1 J. C. Chatagnier, U.S. Pat. No. 4,081,990 PA1 D. J. Rome, Sr. et al., U.S. Pat. No. 4,083,230 PA1 E. L. Potts U.S. Pat. No. 2,953,919 PA1 G. L. Loomis U.S. Pat. No. 3,165,919 PA1 G. L. Loomis U.S. Pat. No. 3,165,920 PA1 C. L. Phillips et al U.S. Pat. No. 3,375,703 PA1 N. F. Brown et al U.S. Pat. No. 3,420,095 PA1 C. F. Phillips U.S. Pat. No. 3,461,961 PA1 C. L. Phillips et al U.S. Pat. No. 3,495,443 PA1 C. L. Phillips et al U.S. Pat. No. 3,800,596 PA1 L. C. Rathburn U.S. Pat. No. 4,468,952
Each shows a type of tubing testing apparatus that includes a single passageway for use with a single testing fluid or liquid and will provide only limited testing capability.
The following patents relate to pressure testing equipment that employs two internal passageways:
In the early approaches to testing pipes, two separate tools were used. The first was a relatively short tool that would be lowered down into the tubing adjacent a coupling area between two separate tubes. Pressure would be applied to expand sealing devices provided on the tool and spaced axially so as to lie on opposite sides of the coupling. Following the application of a predetermined amount of pressure on those seals, normally in the form of rubber packings, an annular chamber would be formed between the seals, the interior surfaces of the joint and the exterior of the tool. A gas would then be pumped into that annular cavity, such as nitrogen, another pressure would be maintained for some desired period of time at the desired pressure. No gas would be detected if the seal in the joint were sound.
Thereafter, gas pressure would be relieved from the test cavity, the seals would be released and the short tool removed from the pipe. A longer tool would then be inserted into the pipe, this time above the joint just tested, in order to test the integrity of the body of the pipe section above that joint. Here again, the longer tool would be provided with axially spaced-apart upper and lower seals which would be activated in order to again form a cavity between the inner and outer surfaces of the pipe and the tool, respectively, and the seals. Water is normally used to test the integrity of the body of the pipe or tubing and water or other liquid would be pumped into the cavity at a desired pressure.
The short tool would normally be five to ten feet in length and gas would be supplied to the small tool normally through flexible hoses that remained connected to the tool. Such hoses and the tool would be lowered into the tubing together with whatever apparatus was used to support the tool during its insertion and removal.
The longer section would be able to test a pipe having a length of about 25-30 feet, and again the water would be supplied through hoses that remained connected to the longer tool. A device for testing the joint area is shown in Loomis U.S. Pat. No. 3,154,940 and for the wall sections of the pipe in Loomis U.S. Pat. No. 3,165,919.
An improvement in this apparatus was a single device which allowed the testing of two different cavities simulataneously. This was accomplished by using three packer or seal assemblies, two being spaced far enough apart to encompass a coupling area, with the test cavity again being formed about the interior of the coupling. By placing another or third seal some distance from the other two seals, it was then possible to test a long length of pipe after having formed a second cavity between that third and the next closest seal, the outer diameter of the tool and inner diameter of the pipe sections therebetween. An example of such a tool is shown in Brown et al, FIG. 27, U.S. Pat. No. 3,420,095.
To this point the art included testing devices that employed one or two passageways and could test only relatively short pipe sections or a single joint and one length of pipe at a time. They were not capable of testing a multiple number of pipe and joint sections along a relatively long tubing string.
In Hailey, U.S. Pat. No. 4,519,238, the problem of how to create longer testing tools was addressed. The objective there was a tool for testing two or three interconnected pipe sections. In a preferred embodiment, a single longitudinal fluid passageway was used to provide the fluid for setting spaced-apart packers along the tool and to also simultaneously provide the fluid used for testing pipe wall sections. A second longitudinal fluid passageway system provided a second fluid for testing the integrity of pipe joint areas. While Hailey stated that any number of such fluid passages may be provided, including one such passageway for each test chamber in each packer; Hailey also recognized that there were space availability problems for such passageways, as well as connection difficulties which practically limited the number of passageways which could be conveniently used. In another embodiment, Hailey used three internal fluid passageways. The first extended the length of the pipe testing tool and provided pressurized fluid that would set all of the packers and also the fluid necessary for performing controlled tests for certain pipe wall segments. A second passageway extended along a portion of the tool provided a source of pressurized gas that would be directed to joint areas bracketed by the tool that could be separately sealed by packers or seals actuated by the first fluid passageway system. The third fluid passageway extended only from the head end of the tool down into the first annular chamber formed below the uppermost packer or seal. Accordingly, the third passageway was designed to only test one annular chamber. Any other wall sections would be tested by the fluid used to set the packers.
The problem associated with such an arrangement was that it did not fulfill Hailey's stated desire of having more control over the testing device, and indeed it created a potentially dangerous situation by employing the very fluid used to set the packers or seals as used to test the pipe wall integrity. The approach adapted by Hailey to allow this dual use of the packer fluid was to provide an unrestricted radial port to conduct the fluid from that first passageway initially into a setting chamber adjacent to the packers which would set the packers at a predetermined pressure ranging from 1200-2000 psi. A second radial port extended from that same passageway system into the annular chamber that was to be established for testing the pipe wall section once the packers were set. The second port included a restriction or orifice which only allowed pressurized fluid to pass into the annular testing cavity after the packer seals were set, presuming they were quick enough. It was believed that such an approach would assume that the packers would be expanded and fully sealed prior to allowing fluid to enter the annular testing chamber defined between two packers. The problem, however, was that the restriction always remained in the line extending back into the first passageway system and also restricted the decrease in pressure within the annular chamber. Thus, if the seals failed, the restriction would prevent fast depressurization of the annular chamber via the internal cavities and the tool leaving a greater pressure in the annular chamber. Occasionally, tools of this nature could fly out of the tubing string.
Accordingly, it is most desirable to provide three separate passageways within a tool, with each being isolated from the other and extending the full length of the tool. By having the packer control system isolated from the water and gas testing passageway systems, a control over the testing operation and the tool itself will be assured.